The Flash takes place in the same universe as the Arrow TV series, and tells us the story of a young Barry Allen, who got his powers after a particle accelerator explodes, leaving him in coma for months. After he wakes up, he discovers that now he has super speed, and end up teaming up with Harrison Wells, Caitlin Snow and Cisco Ramon to become a speedster masked hero, later gaining the name of The Flash.
This show is REALLY well done and sure one of the recent series that I loved the most. It's super fun and don't require prior knowledge of the DC comics. Of course, those who have read the Flash or Justice League comics will have a lot of fun with the Easter Eggs or trying to find out some things before they appear on TV. But anyway, I enjoyed it immensely without needing to go to Wikipedia to look for something that didn't make sense.
It has a nice selection of both friends and foes, both human and meta-human, and all of them have great moments through the season. Although the pacing is not always fast, it's never slow (drum roll) and the show keeps its speed up (drum roll²) so you never get bored or sleepy.